Pruning Effect And Pruning Physiology Of Precious Species Zelkova Schneideriana

With the development of society and economy,people’s material demand has been greatly improved,the demand of fine and precious materials is large.In recent years,China’s precious fine wood has been seriously lacking.The cultivation of fine precious wood is an important goal for the development of planted forests.Pruning measures are particularly important in the cultivation of fine and precious wood.As a precious local wood species,Zelkova schneideriana has a weak research on pruning technology.Therefore,this study takes 6-year-old Zelkova schneideriana plantation as the research object,and explores the effects of different pruning intensities and different pruning seasons on Zelkova schneideriana growth,pruning wound healing,shoot bud germination,and pruning wound healing.Changes in source hormone and nutrient content and their regulatory mechanisms,photosynthetic characteristics and changes in trunk sap flow,and other physiological conditions provide technical support for scientifically formulating Zelkova schneideriana pruning plans.The main results of the study are as follows:1.Zelkova schneideriana are characterized by strong branching ability,many branches,obscure trunk and weak natural pruning ability.The branching characteristics of Zelkova schneideriana will affect the crown shape,and then affect the utilization rate of light energy,nutrient distribution,growth and development of trees.With the increase of ground diameter,the number of branches of Zelkova schneideriana increased.When the ground diameter was 9-10cm,the branch angle,branch diameter and branch length were the largest,which affected the formation of beech trunk,trunk height and volume growth.Pruning in winter has the least effect on the growth of height and ground diameter of Zelkova schneideriana,but pruning in winter will cause a large number of branches to sprout around the trunk and wound of Zelkova schneideriana,and then affect the dry shape and growth of Zelkova schneideriana,as well as the healing of wound,and affect the formation of full and dry talents without knots.In spring pruning,1/3 of the pruning treatment was relatively less sprouting,and 1/3 intensity pruning in spring had the lowest suppression of Zelkova schneideriana height and ground diameter growth and was not significantly different from CK（P>0.05）.2.The photosynthetic capacity between different canopies of Zelkova schneideriana plantation was upper canopy﹥middle canopy﹥lower canopy,and the photosynthetic capacity between different treatments under different pruning intensities was 1/3﹥1/2﹥CK﹥1/4.The content of chlorophyll in each treatment was 1/3 of the pruning intensity content at different growth times（March,May,July,and October）greater than that of other treatments.Appropriate removal of the lower canopy photosynthetic capacity can increase the photosynthetic capacity and chlorophyll content of the preserved canopy to a certain extent.The photosynthetic capacity of the 1/3 pruning treatment has the greatest improvement.3.Under the pruning treatment in winter and spring,the complete healing rate and healing ratio of pruning wound of Zelkova schneideriana between pruning strength were 1/3>1/2>1/4.The wound healing ratio and complete healing rate of prunus Zelkova schneideriana pruning were higher in winter than in spring,but under 1/3 of pruning treatment,there was no significant difference between winter and spring（P>0.05）.Under pruning treatment in winter and spring,the wound healing rate and complete healing rate decreased with the increase of wound diameter,and the wound healing rate and complete healing rate were 100%between 0 and 1.0cm in the wound diameter.4.After the pruning measures were implemented,the IAA,ZR,and GA₃ contents of Zelkova schneideriana buds and stems increased compared with CK.The IAA,ZR,and GA₃contents of leaves at the 8th and 16th weeks after pruning gradually decreased with the increase of pruning intensity.In the second week,the contents of IAA,ZR,and GA₃ in the pruning treatment were all greater than CK,and the content of 1/4 in the pruning treatment was the highest.The content of ABA in leaves,buds and stems was larger than that in CK in pruning treatment.The largest increase in ABA content in leaves and buds was in 1/3 pruning treatment,1/2 processing is the largest.After pruning,the contents of N,P and K in the leaves of Zelkova schneideriana all increased,while the contents of N,P and K in the stem all decreased.The content of N,P and K in leaves,buds and stems of 1/3 pruning treatment fluctuated the least,and the maximum was 1/4 treatment,followed by 1/2 treatment.Pruning measures can affect the regulation and distribution of endogenous hormones and nutritive elements between different organs of Zelkova schneideriana,so that different endogenous hormones and nutritive elements can reach an appropriate content and proportion,so as to meet the endogenous hormones and nutritive elements content required for the growth of Zelkova schneideriana in response to pruning measures.5.The daily variation of trunk fluid flow between different pruning intensities of Zelkova schneideriana showed a similar variation rule between day height and night height in each season,and the maximum and average values of fluid flux between different pruning treatments were summer（July）>autumn（October）>spring（may）on the seasonal scale,and the pruning intensities were CK>1/4>1/3>1/2.Under the condition of continuous sunny weather in summer,the sap appears"noon break";there is a significant lag between the sap of the Zelkova schneideriana trunk and the meteorological factors,and the response of the change of the sap to the meteorological factors is one hour later.The meteorological factors that have a greater impact on trunk sap flow are T,RH,and VDP in that order.The stepped-regression analysis shows that the liquid flux and meteorological factors conform to the multiple linear fitting equation y=56T-5.873 RH+1.058 Rt-1.129 Rn-132.842 S-88.143 VDP-761.239（R²=0.935）.6.Based on the above research results,it is suggested that 1/3 pruning treatment should be carried out in spring before the ground diameter of Zelkova schneideriana is 9-10cm,which is a more suitable pruning scheme for the management of Zelkova schneideriana plantation in actual production.